Endoscopic cannula

ABSTRACT

A cannula comprising a hollow tube made of a biocompatible, thermoplastic polymer, memory shape material, tipped with an injection needle at it distal end, assumes desired shapes as it distally emerges from a lumen or channel of an instrument such as an introducer or endoscope. The desires shape includes a curvature conforming to an inverse tangent function. The cannula may be supplied alone, with or without an injection needle, and in a sterile pouch, for use with a device of an user&#39;s choice that has a suitable lumen or channel to guide the cannula, of the cannula may be used without such an instrument.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of each of (a) U.S. patentapplication Ser. No. 15/722,168 filed Oct. 2, 2017, (b) U.S. patentapplication Ser. No. 15/834,333 filed Dec. 7, 2017, and (c)International Patent Appl. No. PCT/US18/50087 filed Sep. 7, 2018published as WO 2019/051315 on Mar. 14, 2019. Said International PatentAppl. claims priority to said U.S. patent application Ser. No.15/834,333 as well as to U.S. patent application Ser. No. 15/722,168filed Oct. 2, 2017, and said U.S. patent application Ser. No. 15/834,333is a continuation-in-part application of U.S. patent application Ser.No. 15/697,640 filed Sep. 7, 2017 and issued as U.S. Pat. No. 10,286,159on May 14, 2019.

This application incorporates by reference and claims the benefit of thefiling date of each of the above-identified patent applications, as wellas of the applications that they incorporate by reference, directly orindirectly, and the benefit of which they claim.

FIELD

This patent specification pertains to cannulas used primarily in medicalinstruments and procedures although they may have non-medical uses aswell.

BACKGROUND

Flexible cannulas are widely used in medical procedures to pass throughcannula lumens in instruments such as endoscope and introducers andtreat internal patient sites, for example to inject a substance in aninternal organ, to deliver a substance to an internal site, to applyelectrical current or other energy to an internal site, to view aninternal organ, and to extract tissue samples or fluids from an internalsite, to name a few. Such cannulas may also find use in fields otherthan medicine, for example to access internal regions in objects thatare not otherwise easily reachable.

One condition treated with injections in the bladder Overactive Bladder(OAB). In about 2013, the FDA approved treatment of OAB by periodicallyinjecting OnabotulinumtoxinA (Botox) at sites in a pattern along theinner wall of the patient's bladder. Previous methods of deliveringOnabotulinumtoxinA to the bladder have involved inserting a cystoscopein the bladder through the urethra, passing a long metal needle througha lumen or working channel in the cystoscope, and manipulating theentire assembly both laterally and along the axis of the urethra as aunit to inject medication at numerous injection sites in the bladder.Such previous devices and methods have resulted in significant patientdiscomfort and hold the danger off damage to the urethra and surroundingtissue.

A desired placement and pattern of the multiple injections in thebladder are associated with significantly improved treatment outcomes.It is important that devices and methods of injecting OnabotulinumtoxinAinto the bladder offer physicians performing the procedure precisecontrol. However, it had been difficult to create precise injectionpatterns using such previous devices and methods when the scope moveswith the needle when aiming for a new injection site. Moreover, saiddevices are usually not disposable, and must be disassembled andsterilized after each use, making them difficult to maintain andincreasing the risk of contamination or infection. More recently,disposable cannulas with integrated video camera and injection needleshave been discussed. See for example US Published Application2016/0367119 A1 and U.S. Pat. No. 10,278,563.

There are proposals to use cannulas made of shape memory metals thatchange shape after emerging from lumens in devices such as introducers.See Sachveda U.S. Pat. No. 5,607,435 illustrating in FIG. 4 a tubularsection 42 with a leading edge shaped as a surgical needle that curlsafter exiting a straight delivery tube 50. According to the patent, thecurling section is made of metal alloys such as Nitinol. See alsoMcGucken Published Patent Application US 2003/0032929 A1 proposing ashape memory Nitinol infusion needle and mentioning that polymermaterial might be used in some applications for a shaft in which a shapememory stylet moves but not that the polymer material can be shapememory.

SUMMARY OF THE DISCLOSURE

According to some embodiments, a medical device for insertion into apatient's body and injecting medication into internal tissue comprises:an elongated hollow cannula made of a biocompatible, non-metallicmaterial; and an injection needle protruding distally from a distal endof said cannula. The cannula has a first shape when confined by firstexternal forces acting thereon, and a distal portion that reverts to asecond shape when free of said first external forces. The second shapehas a predetermined curvature defined by an inverse tangent function andcomprising two bends in different directions, and the injection needleis radially spaced from an axis of the first shape when the distalportion of the cannula has reverted to the second shape. The cannula issufficiently flexible to assume the first shape when in a workingchannel of an introducer or endoscope but at least the distal portionthereof is sufficiently stiff when in the second shape to force theneedle distally into the tissue when a distal force is exerted on aproximal portion of the cannula and/or introducer or endoscope.

At least the distal portion of the cannula of the medical device canhave a flexural modulus of about 595,000 psi, and/or the entire cannulahave such a flexural modulus. At least the distal portion of saidcannula can be made of polyether ether ketone (PEEK), and/or the entirecannula can be a single hollow tube made of PEEK. The medical device caninclude a working channel configured to exert the first external forceson the cannula, and the cannula can be longer than the working channelsuch that the distal portion of the cannula protrudes distally from theworking channel while a remaining portion of the tube occupies an entirelength of the working channel. The two bends of the distal portion ofsaid cannula of the medical device can be spaced from each other by astraight portion of the cannula, and/or the two bends can be in oppositedirections.

In some embodiments, a medical device comprises an elongated cannulamade of a biocompatible, non-metallic material; the cannula having afirst shape when confined by first external forces acting thereon; thecannula having a distal portion that reverts to a second shape when freeof said first external forces; and the second shape having apredetermined curvature defined by an inverse tangent function andcomprising two bends in different directions. A distal end of thecannula moves radially away from an axis of the first shape as thedistal end moves distally away from the said first external forces.

At least the distal portion of the cannula of the medical device canhave a flexural modulus of about 595,000 psi, and at least the distalportion of the cannula can be made of polyether ether ketone (PEEK). Themedical device can further include a working channel configured to exertthe first external forces on the cannula when the cannula is therein.The medical device can further include an introducer having the workingchannel exerting said first external forces on the cannula when therein.The medical device can further include an endoscope having said workingchannel exerting the first external forces on the cannula when therein.The medical device can further include an injection needle secured toand protruding distally from said distal end of said cannula. The twobends of the distal portion of the tube can be spaced from each other bya straight portion of the tube, and/or the two bends can be in oppositedirections.

In some embodiments a method comprises inserting an elongated hollowcannula made of a biocompatible, non-metallic material into a passage ina patient's body while confining at least a distal portion of thecannula to a first shape by first external forces acting thereon;thereafter gradually moving a distal end of the cannula distally fromsaid confining to thereby: cause the distal portion of the cannula togradually revert to a second shape that has a predetermined curvaturedefined by an inverse tangent function and comprises two bends indifferent directions; and cause the distal end to move radially from anaxis of said first shape; and injecting medication at selected injectionsites of internal tissue of said patient with an injection needleprotruding distally from a distal end of the cannula; wherein theinjection sites are spaced from each other by distances that depend on adistal distance of said injection needle from said first externalforces.

The confining of the method can comprise enclosing the cannula in aworking channel of an introducer or endoscope.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a medical injection assembly, according to someembodiments.

FIG. 2 is a cross-section of a sheath or introducer, according to someembodiments.

FIG. 3 is a cut-away isometric view of a sheath or introducer, accordingto some embodiments.

FIG. 3a illustrates a distal portion of a biocompatible polymer cannulathat has reverted to a curvature conforming to an inverse tangentfunction after exiting a distal end of an introducer, according to someembodiments.

FIG. 3b illustrates a distal portion of a biocompatible polymer cannulathat has reverted to a curvature of over 90 degrees after exiting adistal end of an introducer, according to some embodiments.

FIG. 3c illustrates a distal portion of a biocompatible polymer cannulathat has a curvature conforming to an inverse tangent function and canbe used with alternative introducers or endoscopes that have a cannulalumen or a working channel, or by itself, with or without an injectionneedle at its distal tip, according to some embodiments.

FIG. 3d illustrates a distal portion of a biocompatible polymer cannulathat has a curvature of over 90 degrees and can be used with alternativeintroducers or endoscopes that have a cannula lumen or a workingchannel, or by itself, with or without an injection needle at its distaltip, according to some embodiments.

FIG. 3e illustrates a distal portion of a biocompatible polymer cannulathat has a curvature of less than 90 degrees and can be used withalternative introducers or endoscopes that have a cannula lumen or aworking channel, or by itself, with or without an injection needle atits distal tip, according to some embodiments.

FIG. 4 is a cross-section of a handle of an introducer, according tosome embodiments.

FIG. 5A is a side view of a cannula exiting a sheath or introducer,according to some embodiments.

FIG. 5B is a side view of a cannula exiting a sheath or introducer,according to some embodiments.

FIG. 5C is a side view of a cannula exiting a sheath or introducer,according to some embodiments.

FIG. 6 is an isometric view of a plunger body, according to someembodiments.

FIG. 7 is a bird's eye view of a finger grip, according to someembodiments.

FIGS. 7a and 7b are two perspective views from different viewpoints thatillustrate another example of a syringe that can be coupled to a fluidconnector.

FIG. 8A is a frontal view diagram of a bladder injection pattern,according to some embodiments.

FIG. 8B is a side view diagram of a bladder injection pattern, accordingto some embodiments.

DETAILED DESCRIPTION

A detailed description of examples of preferred embodiments is providedbelow. While several embodiments are described, the new subject matterdescribed in this patent specification is not limited to any oneembodiment or combination of embodiments described herein, but insteadencompasses numerous alternatives, modifications, and equivalents. Inaddition, while numerous specific details are set forth in the followingdescription in order to provide a thorough understanding, someembodiments can be practiced without some or all these details.Moreover, for the purpose of clarity, certain technical material that isknown in the related art has not been described in detail in order toavoid unnecessarily obscuring the new subject matter described herein.Individual features of one or several of the specific embodimentsdescribed herein can be used in combination with features of otherdescribed embodiments or with other features. Further, like referencenumbers and designations in the various drawings indicate like elements.

This patent specification describes special, hollow, biocompatiblepolymer cannulas configured to pass through lumens or working channelsof a variety of devices and revert to desired predefined curvaturesafter distally exiting. The lumens of channels can be straight or curveddifferently from the predefined curvatures to which the polymer cannulasrevert when out of those lumens or channels. The lumens or channels canbe in any one of a great variety of instruments, including withoutlimitation cystoscopes and other endoscopes of introducers. Thecurvatures to which the cannulas revert can be as suitable for aspecific need or application. The curvature to which a cannula revertscan have a single bend of any desired angle up to 180 degrees relativeto a long axis of the cannula, and in some cases can exceed 180 degrees.Another curvature to which a cannula reverts can have two bends inopposite direction, i.e. the curvature can conform to an inverse tangentfunction. Other curvatures also are possible, e.g., more than two bends,or bends in different planes, etc. The cannulas typically have a distalportion that reverts to the predefined curvatures while the rest of thecannulas are straight or have different curvatures. The cannulastypically have proximal ends that are accessible, for example to injectfluids or other substances into the proximal end of the cannulas or towithdraw substances through the proximal ends. For example, the proximalends of the cannula can extend proximally from the lumens or workingchannels for such access.

For use of such cannulas to inject substances at an internal site in apatient, injection needles can be secured to distal tips of thecannulas. For other purposes, such as infusing a substance into orwithdrawing a substance from an internal site, the distal tips of thecannulas may be simply open or may be shaped as desired or needed.

The lumens or working channels through which the cannulas pass can be ininstruments such as endoscopes, introducers, and other devices that canguide cannulas and allow them to protrude distally from the device. Suchdevices can include viewing components, such as a video camera and alight source at a distal end, or a scope channel in which a viewingdevice can be inserted and may include one or more lumens in additionfor the lumen or working channel for the cannulas, e.g., fluid passagesor working channels for surgical instruments. Alternatively, the devicesguiding the cannulas can be simply guides, with no viewing facilitiesand may or may not have any additional lumens or channels.

One example of such cannulas, as used to inject Botox or othermedication into a pattern of injection sides at the inner wall of apatient's bladder, is described in commonly owned U.S. patentapplication Ser. No. 15/697,640, now U.S. Pat. No. 10,286,159, to whichthis patent specification claims priority. This patent specificationrecapitulates that example as illustrative of one use of such cannulasand adds disclosure of other examples of uses of such cannulas.

In the example of treating a patient's bladder with Botox (for OAB) orother medication for other medical conditions, this patent specificationhighlights the discovery that certain biocompatible polymers can beadvantageously configured to inject medication in a desired pattern ofsites over a relatively wide area in the interior wall of a bladder withlittle or no lateral movement of an introducer. This is made possible inpart by using a memory shape, biocompatible polymer cannula with adistal portion that revert to a predetermined curvature after exiting acannula lumen. One particularly important predetermined curvature hastwo bends in opposite directions. While it may have seemedcounterintuitive that such curvatures of a thin, non-metal cannula wouldprovide enough support for a needle to be pushed into tissue andmaintain a desired orientation, this curvature has been proved highlyuseful and has been particularly helpful in injecting at sites arrangedover a relatively large area by only rotating and advancing the cannula,with no or only slight side-to-side motion that can harm tissue. Anothersignificant benefit is that the memory shape polymer used for thecannulas described in this patent specification is much less expensivethan the metals such as Nitinol that have been traditionally used asmemory shape devices. Other benefits are discussed in said patent andfurther below.

FIG. 1 illustrates a medical injection assembly 1 comprising anintroducer 100 that includes a handle 101, a sheath 102, and a scopelumen 103 extending from a first proximal end of the handle 101 to adistal end of the sheath 102, according to some embodiments. The scopelumen 103 is configured to receive an endoscope 110 at the firstproximal end of the handle 101 and hold the endoscope in a desiredposition. A cannula lumen 104 extends from a second proximal end of thehandle 101 to the distal end of the sheath 102 and receives a cannula109 at a second proximal end of the handle 101 and guides the cannula109 in lumen 104. The introducer 100 may further comprise a fluid line105 having a distal end in fluid communication with the scope lumen 103or with a port at the distal end of introducer 100.

FIGS. 2 and 3 illustrate scope lumen 103 and cannula lumen 104 in sheath102 of an introducer 100, according to some embodiments. Scope lumen 103may be configured to receive a variety of endoscopes 110 forilluminating and visualizing target tissue within the body. In someembodiments, the endoscope 110 may be a cystoscope. The inside diameterof the scope lumen 103 preferably fits industry standard cystoscopesknown in the art. In preferable embodiments, the scope lumen 103preferably has an inside diameter of about 4 mm to about 5 mm.

The cannula lumen 104 preferably has an inner diameter of about 1 mm toabout 2 mm. The inner diameter or lumen 104 is only slightly more thanthe outside diameter of cannula 109. The walls of sheath 102 preferablyare thin to reduce the outer diameter of the sheath and therebyfacilitate passage through a patient's urethra while maintainingstrength and rigidity. In preferred embodiments, the sheath walls mayhave a thickness of about 0.1 mm to about 0.4 mm. The sheath 102 may becomprised of polyether block amides, polyethylene, or other materialswith similar rigidity characteristics.

Cannula 109 is a hollow tube made of a biocompatible thermoplasticpolymer such as polyether ether-ketone (PEEK), with an outside diameterabout 1-2 mm. At least a distal portion of cannula 109 is a shapememory, biocompatible material that reverts to a predetermined curvatureafter it projects distally from cannula lumen 104. The material and theinside and outside diameters of cannula 109 are carefully selected tomeet two mutually exclusive requirements” one is to make the distalportion of cannula 109 stiff so it can help push an injection needleinto the inner wall of a patient's bladder when said distal portion iscurved, for example in an S-shape, and the other is to make that distalportion of cannula 109 flexible so it can be straight when inside acannula lumen 104. Preferably, the polymer of cannula 109 has a flexuralmodulus of about 595,000 psi. Notably, such a flexural modulus allowsthe user of the device to insert the needle into bladder tissue withoutcausing the cannula to bend or deform in a clinically significantmanner. To a skilled person such as a urologist, this means that wheninjecting in the bladder, the needle would not harm bladder tissue morethan has been acceptable in standard-of-care medical practice forconventional injections in the bladder wall and that the visible part ofthe needle would generally stay in the field of view of a typicalendoscope viewing. The bladder wall of adults typically is about 3.5-5.0mm thick, or an injection needle about 3.0 mm thick would stay in thebladder wall. Some deviation in the needle trajectory during insertionis common and is clinically insignificant so long as it leaves only atemporary tissue disruption, i.e., a disruption that typically clears ina few days, as distinguished from a disruption that punctures thebladder wall or interferes with bladder function for more than a fewdays. For example, if the cannula deforms so much that the needle cannotpenetrate into the bladder wall at a desired injection site or if thecannula bends or deforms so much that the tissue is disrupted to thepoint of not containing the medication being injected, or if the cannulabends or deforms so much that the needle being forced into tissue opensa slot in tissue rather than a hole about the diameter of the needle,this can be considered a medically significant deformation of thecannula. For example, for a typical adult with a bladder wall thicknessabout 35-5.0 mm, and a 23-gauge injection needle (about 0.58 mmdiameter, typically used to inject medication in the bladder wall) thatis 3 mm long from the distal tip of the cannula to the sharp point ofthe needle (again, typical needle length), a deviation in trajectorywithin 15-20 degrees from the orientation at the start of insertionwould not be clinically significant.

FIG. 3a illustrates more clearly an example of a desirable curvature ofa distal portion of cannula 109 from which injection needle 114protrudes distally. This curvature conforms to an inverse tangentfunction. As illustrated, the distant portion of cannula 109, whichprotrudes distally from the distal end of cannula lumen 104 inintroducer 102, has reverted to a curvature that has two bends orinflections in opposite directions and thus can be said to be generallyS-shaped. How cannula 109 assumes this curvature is explained below inconnection with FIGS. 5A-C. FIG. 3b illustrates an example of analternative curvature—here the distal portion of cannula 109 thatprotrudes distally from cannula lumen 104 has reverted to a curvaturecharacterized by a single bend that can be 90 degrees or more and even180 degrees or more, as may be desirable for a specific medical or otherprocedure.

FIGS. 3c-e illustrate cannula 109 as in may be used alone or with anyone of a variety of instruments that can guide it and from which it canemerge distally to revert to a predetermined curvature. Am injectionneedle 114 can be secured at the cannula's distal tip or the cannula canbe used without such a needle. Cannula 109 shown in FIGS. 3c-e can besupplied to users alone, with or without an injection needle 114 at itstip. Preferably, cannula 109, with or without needle 114, would besupplied in a sterile package that the user can open when needed and usethe cannula as desired. As non-limiting examples, a user may passcannula 109, with or without needle 114, through a lumen or workingchannel of a device such as an introducer or an endoscope or some otherguide. Reference numeral 104 schematically illustrates any one of suchvariety of instruments that may be the same or different from introducer100 shown in FIG. 1-3 b. As other non-limiting examples, a user may usethe cannula of FIGS. 3c-3e without an introducer and with or without aneedle.

In each of FIGS. 3c-3e , cannula 109 is a hollow tube of a shape memory,biocompatible polymer. Several different predetermined curvatures towhich a distal portion of the cannula reverts are illustrated. In FIG.3c , the curvature conforms to an inverse tangent function; in FIG. 3d ,the curvature is a bend that is over 180 degrees but can be any angle upto an even exceeding 180 degrees; and in FIG. 3e the curvature is asingle bend.

FIG. 3e schematically illustrates a sterile package 105 enclosingcannula 109; like sterile packages can enclose the cannulas of FIGS. 3cand 3d . In each case, a needle 114 may be secured to the cannula or maybe absent. In some embodiments, the entire instrument illustrated inFIG. 1 may be delivered to a user enclosed in a like sterile pouch,typically without syringe 111.

The cannula 109 that has been used in a medical procedure typically isdiscarded as medical grade waste rather than being sterilized and usedin another procedure to thereby eliminate or reduce the danger ofpossible contamination in other procedures.

The predefined curvatures discussed above exist when the cannula is freeof external forces that would prevent it from assuming such curvatures.When subjected to external forces, such as when confined in a straightlumen or working channel, the cannula would extend along a straight axisif the lumen or channel is straight or would assume the curvature of thelumen or channel that is not straight.

Returning to the example of using the cannula to inject medication in apatient's bladder, FIG. 4 illustrates handle 101 of an introducer 100according to some embodiments. A scope lumen 103 extends from a proximalend of the handle 101 and may be configured to receive an endoscope 110from a proximal end of the handle 101. A scope seal 112 is positioned ata proximal end of the handle 101 to engage endoscope 110. The scope seal112 is a material with an appropriate coefficient of friction to holdendoscope 110 in place. The scope seal 112 preferably comprisessilicone.

The cannula lumen 104 extends from a proximal end of the handle 101 andis configured to receive cannula 109 from a proximal end of the handle101. A cannula seal 113 is at a proximal end of the handle 101 to engagecannula 109. The cannula seal 113 preferably is made of a material withan appropriate coefficient of friction to hold a cannula 109 in place.The material of the cannula seal 113 preferably comprises silicone. Thehandle 101 further comprises a fluid line 105 in fluid communicationwith the scope lumen 103. The distal end of the fluid line 105 connectsto the scope lumen 103 via a watertight fluid connector. In yet otherembodiments, the distal end of the fluid line 105 may be integrateddirectly into the scope lumen 103 via known manufacturing methods suchas various molding techniques, welding, 3D printing, adhesives, etc. Thefluid line 105 may comprise a second fluid connector 106. In preferredembodiments, the second fluid connector 106 may be a luer lock. Thefluid line 105 may further comprise a pinch valve 107. The pinch valve107 may control the flow of fluid form a fluid source through the fluidline 105 and into the scope lumen. A port at the distal end of the scopelumen can be provided for outflow or inflow of fluid. FIG. 4 furtherillustrates a fluid connector 115 coupled to a proximal end of cannula109 and provided with a pinch valve 113 to selectively deliver fluidsinto cannula 109 for injecting through needle 114.

The needle 114 may be a commercially available hypodermic needlesuitable for performing injections of OnabotulinumtoxinA or otherdesirable medication. The outer diameter of the needle 114 is slightlyless than the diameter of the cannula 109, so that the needle can befriction-fitted in the cannula. For example, the needle 114 may be a23-gauge needle and may extend past the cannula 109 about 1.0 mm toabout 3.0 mm in length. In such configurations, the distal tip of thecannula 109 acts as a circumferential wall that helps keep the needle114 from penetrating into the target tissue past the distal tip of thecannula 109.

FIGS. 5A-5C illustrate how a cannula 109, with a needle 114 attached toits distal tip, changes it curvature as it moves distally in cannulalumen 104 such a distal portion of the cannula protrudes distally fromthe cannula lumen. When the distal portion of cannula 109 is entirelywithin the cannula lumen, the cannula assumes the shape dictated by theexternal forces the cannula lumen exerts. If the cannula lumen isstraight, so is the distal portion of the cannula while entirely in thecannula lumen. However, when the cannula 109 is made of the shape memorybiocompatible polymer discussed above, as the distal portion of thecannula starts emerging distally from cannula lumen 104, the part of thecannula that has emerged starts reverting to its predetermined shape.FIG. 5A illustrates an early stage, in which a relatively short lengthof cannula 109 has emerged and has reverted to a curvature of a singlebend down. FIG. 5B illustrates a stage in which a greater length ofcannula 109 has emerged and still has only a single bend. FIG. 5Cillustrates a stage in which the entire desired distal portion ofcannula 109 is out of cannula lumen 104 and has reverted to apredetermined shape conforming to an inverse tangent function, with twobends of inflections in opposite directions.

The vertical distance between the distal tip of cannula 109 and a longaxis of cannula lumen 104 changes in the course of movement of cannula109 distally out of cannula lumen 104. This distance is relatively smallin FIG. 5A, greater in FIG. 5B, and greatest in FIG. 5C. One benefit ofthis feature is discussed in connection with FIGS. 8A-B.

FIGS. 6-7 illustrate a syringe 111 that can be coupled to fluidconnector 115 for delivery of fluid such as medication for injection ina patient's bladder through cannula 109 and needle 114. Syringe 111comprises a syringe barrel (not seen in these FIGs.) and a plunger body116 having a first portion 117 proximate the proximal end and secondportion 118 proximate the distal end, wherein the first portion 117 hasa plurality of corresponding detents 119 on opposite sides of the firstportion 117. The syringe 111 may also comprise a sealing cap 120attached to the distal end of the plunger body 116 and a finger grip 121comprising two paddles 122. The finger grip may be configured to beremovably coupled to the plunger body 116 and to interact with thedetents 119 to provide audible and tactile feedback to a user when theplunger body 116 is pushed through the finger grip 121 in a distaldirection. The second portion 118 may fit into commercially availablesyringe barrels with the sealing cap 120 forming a watertight sealwithin the syringe barrel. In preferred embodiments, commerciallyavailable 10 cc syringe barrels may be used. The finger grip 121 may beconfigured to clip on to the plunger body 116. The finger grip 121 mayinclude tabs 123 on the interior of both paddles 122. The tabs 123 mayfit into grooves between the detents 119 on the first portion 117. Whenthe user pushes the plunger body 116 in a distal direction into thesyringe barrel, the detents 119 provide resistance against the movementuntil the tabs 123 bend enough to clear a set of detents 119 and fitinto the next set of grooves. The detents 119 may be spaced along thefirst portion 117 such that clearing one set of detents 119 results inan ejection of a specific amount of fluid from the syringe. In preferredembodiments, clearing one set of detents would result in the ejection of1 cc of fluid from the syringe. When the user causes tabs 123 to clear aset of detents 119 and the tabs 123 come to rest in the subsequentgrooves, the user is provided with tactile and audible feedback toindicate that one such predetermined unit of fluid has been ejected fromthe syringe.

FIGS. 7a and 7b are two perspective views from different viewpoints thatillustrate another example of a syringe that can be coupled to fluidconnector 115. A syringe barrel 300 has a coupler 305 at a distal endthat is shaped and dimensioned to fit connector 115 and a finger hold301 at a proximal end that has a paddles or wings 306, 307 and aflexible tab 302. A plunger body 303 slides in barrel 300 and has at itsdistal end a cap 308 that forms a seal against the inside wall of barrel300. Plunger body 303 has detents 304 along at least one of its longwalls that flexible tab 302 engages as the plunger body moves relativeto the barrel.

FIGS. 8A-8B illustrate therapeutically effective patterns of injectionsites according some embodiments. It has been found beneficial todisperse the injections of medication such as OnabotulinumtoxinA acrossthe bladder tissue. In preferred embodiments, injections patterns maycomprise three concentric semi-circles in the lower half of the bladderwith radii A, B, and C. Such an injection pattern may be created bymoving the cannula 109 distally until the needle 114 is at a distance Afrom the long axis of the sheath 102 of the introducer 100 and rotatingone or both of introducer 100 and cannula 109 until the needle 114 is atinjection site 200. The introducer 100 and/or cannula 109 are then moveddistally to penetrate the bladder's inner wall with injection needle 114and inject OnabotulinumtoxinA or other medication. The needle 114 isthen withdrawn from the bladder wall by proximally moving cannula 109alone or together with introducer 100 and the introducer and/or thecannula are rotated about the long axis of the introducer until theneedle 114 is at injection site 201, and the injection process isrepeated. Once the injection pattern for the semi-circle with radius Ais complete, the cannula 109 may be moved distally relative tointroducer 100 (and the introducer may be moved proximally or distallyas needed) until the needle 114 is at a distance B from the axis definedby the sheath 102 of the introducer 100, and the previous steps can berepeated to create the injection patterns for the semi-circles withradii B and C. Preferably, A is approximately 0.43 inches, B isapproximately 0.8 inches, and C is approximately 1.2 inches. By rotatingthe introducer 100 and/or cannula 109 about the introducer's long axisto position the needle rather than moving the introducer 100 laterallyor pivoting it about an axis transverse to the long axis, the patientexperiences less discomfort and possible injury from stretching of theurethra.

A method for treating overactive bladder comprises inserting anendoscope 110 into a scope lumen 103 of an introducer 100, according tosome embodiments. The method may further comprise inserting a cannula109 into a cannula lumen 104 of the introducer 100, the cannula 109configured such that the distance between the distal tip of the cannula109 and the axis defined by the sheath 102 of the introducer 100increases as the cannula 109 is moved in a distal direction out of theintroducer, wherein a syringe 111 filled with OnabotulinumtoxinA orother medication is coupled to the proximal end of the cannula 109. Themethod may further comprise guiding the introducer 100 through theurethra of a patient to the patient's bladder. The method may furtherinclude extending the distal portion of the cannula 109 past the distalend of the introducer 100 until a needle 114 attached to the distal endof the cannula 109 is placed at a desired radial distance from the longaxis defined by the sheath of the introducer. The method may furthercomprise rotating the introducer 100 and/or cannula 119 to position theneedle 114 at a desired position. The method may further comprise movingthe introducer and/or the cannula in a distal direction to insert theneedle 114 into the bladder. The method may further include activatingthe syringe 111 to inject OnabotulinumtoxinA or other medication intothe bladder. The method may further include moving the introducer 100and/or the cannula 109 in a proximal direction to withdraw the needle114 from the bladder. The method may further include repeating theextending, rotating, moving distally, activating, and moving proximallysteps until a therapeutically effective amount of OnabotulinumtoxinA orother medication has been injected in a therapeutically effectivepattern into the bladder.

An alternative method comprises enclosing a cannula 109, with or withoutan injection needle 114, in a sterile pouch and delivering the pouch toa user. The method further comprised opening the sterile pouch andpassing the cannula through an lumen or channel of a device such as anintroducer, endoscope or some other guide that may or may not be alreadyinserted into a patient's cavity. The method further comprises advancingthe cannula distally until a distal portion thereof starts protrudingdistally from such lumen or channel and begins to revert to itspredetermined curvature. The method further includes advancing thecannula distally even more relative to a distal end of the lumen orchannel, so more of the distal portion of the cannula reverts to itspredetermined shape, and using the cannula such as to inject a substanceinto a patient's bladder or deliver or inject a substance into anotherbody cavity. The cannula is them withdrawn from the patient, alone ortogether with the instrument through which it passed, and the cannula109 is discarded along with any needle 114 as medical grade waste.

Although the foregoing has been described in some detail for purposes ofclarity, it will be apparent that certain changes and modifications maybe made without departing from the principles thereof. There can be manyalternative ways of implementing both the processes and apparatusesdescribed herein. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the body of workdescribed herein is not to be limited to the details given herein, whichmay be modified within the scope and equivalents of the appended claims.Numerous specific details are described to provide a thoroughunderstanding of the disclosure. However, in certain instances,well-known or conventional details are omitted to avoid obscuring thedescription.

1. A medical device for insertion into a patient's body and injectingmedication into internal tissue, said device comprising: an elongatedhollow cannula made of a biocompatible, non-metallic material; aninjection needle protruding distally from a distal end of said cannula;said cannula having a first shape when confined by first external forcesacting thereon; said cannula having a distal portion that reverts to asecond shape when free of said first external forces; said second shapehaving a predetermined curvature defined by an inverse tangent functionand comprising two bends in different directions; whereby said injectionneedle is radially spaced from an axis of said first shape when saiddistal portion of the cannula has reverted to said second shape; andwherein said cannula is sufficiently flexible to assume said first shapewhen in a working channel of an introducer or endoscope but at leastsaid distal portion thereof is sufficiently stiff when in said secondshape to force said needle distally into said tissue when a distal forceis exerted on a proximal portion of the cannula and/or introducer orendoscope.
 2. The device of claim 1, in which at least said distalportion of said cannula has a flexural modulus of about 595,000 psi. 3.The device of claim 2 in which the entire cannula has said flexuralmodulus.
 4. The device of claim 1, in which at least said distal portionof said cannula is made of polyether ether ketone (PEEK).
 5. The deviceof claim 4 in which the entire cannula is a single hollow tube made ofPEEK.
 6. The device of claim 1, further including a working channelconfigured to exert said first external forces on said cannula.
 7. Thedevice of claim 6, wherein said cannula is longer than said workingchannel such that said distal portion of the cannula protrudes distallyfrom the working channel while a remaining portion of the tube occupiesan entire length of the working channel.
 8. The device of claim 1, inwhich said two bends of the distal portion of said cannula are spacedfrom each other by a straight portion of the cannula.
 9. The device ofclaim 1, in which said two bends are in opposite directions.
 10. Amedical device comprising: an elongated cannula made of a biocompatible,non-metallic material; said cannula having a first shape when confinedby first external forces acting thereon; said cannula having a distalportion that reverts to a second shape when free of said first externalforces; and said second shape having a predetermined curvature definedby an inverse tangent function and comprising two bends in differentdirections; whereby a distal end of said cannula moves radially awayfrom an axis of said first shape as said distal end moves distally awayfrom said first external forces.
 11. The device of claim 10, in which atleast said distal portion of said cannula has a flexural modulus ofabout 595,000 psi.
 12. The device of claim 11, in which at least saiddistal portion of said cannula is made of polyether ether ketone (PEEK).13. The device of claim 10, further including a working channelconfigured to exert said first external forces on said cannula when thecannula is therein.
 14. The device of claim 13, further comprising anintroducer having said working channel exerting said first externalforces on the cannula when therein.
 15. The device of claim 13, furthercomprising an endoscope having said working channel exerting said firstexternal forces on the cannula when therein.
 16. The device of claim 10,further comprising an injection needle secured to and protrudingdistally from said distal end of said cannula.
 17. The cannula of claim10, in which said two bends of the distal portion of said tube arespaced from each other by a straight portion of the tube.
 18. Thecannula of claim 10, in which said two bends are in opposite directions.19. A method comprising: inserting an elongated hollow cannula made of abiocompatible, non-metallic material into a passage in a patient's bodywhile confining at least a distal portion of said cannula to a firstshape by first external forces acting thereon; thereafter graduallymoving a distal end of said cannula distally from said confining tothereby: cause said distal portion of said cannula to gradually revertto a second shape that has a predetermined curvature defined by aninverse tangent function and comprises two bends in differentdirections; and cause said distal end to move radially from an axis ofsaid first shape; and injecting medication at selected injection sitesof internal tissue of said patient with an injection needle protrudingdistally from a distal end of said cannula; wherein said injection sitesare spaced from each other by distances that depend on a distal distanceof said injection needle from said first external forces.
 20. The methodof claim 19, wherein said confining comprises enclosing said cannula ina working channel of an introducer or endoscope.